TouchDesigner | Container Display

A quick one today that addresses problems I didn’t know that I had until I decided that I wanted to show off. In Wonder Dome I’m finding that sometimes the best way to build a scene is to use methods encapsulated inside of a container that make some change to some source imagery. This approach gives me a quick access to the parameters that I’m the most likely to use in a given method, without requiring that I always dive into the container to make changes. For example, I’ve build a handy tool for moving video assets around in the dome. This is fantastic, but if I drop this container into another container that needs its own set of buttons I quickly end up with a mess. Here’s an example of what I’m talking about:

Looking at this container from the root folder I can the control panels for this network, and for it’s child. There are lots of ways to address this. I might, for example, just dive into the container find the child container and turn off its display parameter.

That’s a fine approach if I’m only working with a couple of different scenes, but what happens when I suddenly have 10 or 20 scenes in a given network, each with a number of containers with control panels inside of them? Then I have a headache on my hands as I have to methodically go through and carefully disable each of the containers that I don’t want displayed.

We can solve this problem by using a python expression to conjure some TouchDesigner black magic. I’m going to solve this problem by asking my encapsulated containers to look at their parent operator and to complete a simple logical operation. When I’m ready to lock down a scene in my network, I add a capital “P” to the name of the container – for me this means it’s “P”erformance ready.

Now, instead of toggling that display parameter on my encapsulated container instead I’m going to use this expression:

0 if me.parent().name[0] == “P” else 1

“What on earth does this mean?!”
We can call for the name of our parent with the following expression:

me.parent().name

Better yet, we can ask for a specific character in from that name. If we ask for the character in the 0 position (remember that in programming languages 0 is often the first number in a list), we get the first letter from the name of our parent operator. Putting these two ideas together we get the expression:

me.parent().name[0]

Alright, now that’t we have the fist character from our parent operator’s name, let’s do a simple logical operation. Using an if else statement we can set one of two values. In this case I’m toggling between the values 0 or 1 (off or on). The syntax of this starts with the value if your logical operation is true, and then specifies what value to use if that statement is false. With this in mind, the whole expression is:

0 if me.parent().name[0] == “P” else 1

Alright, so if we were to look at our expression as a sentence it might read something like: “Hey TouchDesigner, if my parent’s name starts with the letter ‘P’ set this value to 0, otherwise leave it as 1.”

Alright, now that we’ve written our expression in the right place, let’s see what it’s doing.

Now we have a quick way to turn child control panels on and off without needing to dive into the container and hunt for our container display parameters.